Start the bowline on a bight by tying a bowline using a loop (bight) instead of a single rope. Make the overhand loop as normal and bring the bight through and around the entire knot and tighten securely before putting weight on it.

Figure Eight

See The Ashley Book of Knots # 570, p. 95.Grog notes:"The Figure Eight provides a quick and convenient stopper knot to prevent a line sliding out of sight, e.g., up inside the mast. Its virtue is that, even after it has been jammed tightly against a block, it doesn't bind; it can be undone easily. This virtue is also, occasionally, a vice. The figure of eight can fall undone and then has to be retied."